The ajax_showOptions function takes three arguments. The first one should always be "this", i.e. a reference to the text field. The second one is just a String that is sent to the file on the server. This is useful in case you are applying this feature to more than one text field. If you do, this string is something you could check on on the server(example: if "getCountriesByLetters" is set, find Countries, if "getStatesByLetters" is set, get states etc.). The last argument is always event.
